Process for purifying and bleaching heavy spar



Patented Mar. 20, 1928.

" UNITED STATES,

m1. .nnnns, or anannsnune, GERMANY.

rnocnss non PURIFYING m BLEAonmo HEAVY SPA-R.

1K0 Drawing. Application filed December 22, 1925, Serial No. 77, l82,'and in Germany December 24, 192*.

This invention relates to a process of bleaching of heavy spar. Proposals have been made to drawv from the heavy spar the foreign coloring matter consisting: mainly of iron compounds b boiling it with acids, as, for instance, wit sulphuric acid. The results attained by the method are not satisfactory probably owing to the fact that the iron oxides (which are the principal impurities in the spar),dissolve only with great difliculty and incompletely in acids.

I have discovered that good bleaching results are obtained by treatment with chlorine, especially with nascent chlorine, be-

cause the iron oxides are quickly and easily is finally drawn ofl and may be frequently used again for new processes.

Example.

100 kilogrammes of roastedand ground heavy spar are well mixed with 2 to 3 per cent of manganese dioxide. This mixture is then brought into about kilogrammes of concentrated commercial hydrochloric acid and the mixture is then heated by steam until completely decolorized; I

The mixture is then allowed to settle, the acid drawnoff from'the spar, the latter is Washed by means of water until neutral reaction and is then dried.

I claim v 1. Process of purifying and bleaching heavy spar consisting in well mixing the ground spar with about 2 to 3% of manganese dioxide, treating the mass with strong hydrochloric acid, heating sufliciently to cause reaction and thereafter washing.

2., Process of purifying and bleachin heavy spar consisting in mixing the ground spar with manganese dioxide and heating this mixture with hydrochloric acid and washing.

3. Process of purifying and bleaching heavy spar consisting in roasting and grinding the spar, mixing with manganese dioxide and heating the mixture with. hydrochloric acid and washing.

In testimony whereof I afiix my signature.

KARL EBERS. 

